Taken from mortec.com
Many folks want to know where to look for these Chevy engine casting numbers and codes on blocks and cylinder heads so we decided to put these pages with photos together to help you find them. Most are easy to find once you know where to look. There may be a great deal of grease and crud covering them that will have to be cleaned before you can read them. Also trying to read them while the motor is in a vehicle can also be harder, especially the block casting numbers and casting dates at the rear of the block. Hang in there, if you try, you can use a mirror and a little patience for the hard to see and reach areas. Some folks also use a piece of aluminum foil to make a rubbing of the numbers and dates on the rear ledge of the block. Others have used children's Playdoh to make an impression of the numbers.
Keep in mind that some of the numbers or letters can be difficult to read. A "6" can look like an "8" or an "8" can look like a "3". A upper case letter "I" can look like the numeral "1" and visa versa. Some times part of the number may be missing. A "T" can have the top horizontal part of the letter missing making it look like the upper case letter "I" or a lower case letter "l".
Remember that you have to look at ALL of the numbers, features and parts characteristics to figure out what it is you are looking at. A number of the casting dates refer only to the year of the decade so you will have to see which other features the part has to determine which decade it was made in. Some casting dates do have the year and the decade indicated, making it easier.
We are always looking for new Chevy engine castings numbers. If you have some information you want to share with us and our visitors, send us an email with the data. Right now we are limiting our listings to Chevy V-8 blocks, cranks and heads. As new castings are released on late models keep your eyes open for the new numbers. Thanks!
The diagram above shows where each of the casting identifiers is located on the engine. (1) shows the location of the HEAD CASTING NUMBERS and the HEAD CASTING DATE located under the valve covers, in the rocker arm valley. (2) shows the position of the BLOCK CASTING DATE on the rear ledge of the block near the bell housing mounting surface. If you have an early big block or a late model smallblock, the BLOCK CASTING DATE may be on the passenger side of the engine block, (see 2A), instead of the rear ledge of the block. Some smallblock blocks may also have the BLOCK CASTING DATE on the driver's side of the block. (3) indicates the position of the BLOCK CASTING NUMBER. Later blocks may also have the size of the engine displacement in liters listed at (3). (4) indicates the position of the ENGINE ASSEMBLY DATE/SUFFIX CODE and partial VIN code information on the front of the block. (5) on the rear flange of the block, on the drivers side near the oil filter pad, is an alternate block location for some VIN codes. (6) indicates the sides of the block where some blocks may have the size of the motor indicated in cubic inches or in liters. The last three numbers of the block casting number may also be repeated in this location.
CHEVY V-8 BLOCK CASTING NUMBER LOCATIONS
There are three block casting number types to look for: the block CASTING NUMBER, the block CASTING DATE and the ENGINE ASSEMBLY DATE/SUFFIX CODE.
BLOCK CASTING NUMBER
The block casting number on smallblock and big block Chevy V-8 motors is located on a ledge found at the rear of the block, most often on the driver's side. This ledge is below the deck of the block and the ledge forms the mating surface between the block and the transmission bellhousing. Some of the later model blocks have the casting number on the passenger side of this ledge. The number itself can have 6, 7 or 8 numeral digits. They might look like this "361959" or "3970010" or "14015445". The block casting numbers do not have any letters in them. There are sometimes individual letters found on blocks like "GM" or "CFD" for the Central Foundry Division, but they are not part of the block casting number. Also some of the later blocks have the size of the motor shown in liters. You may see a "5.0" (305) or "5.7" (350) cast on the rear ledge of a smallblock or a "7.4" on the side of a big block 454. On the side of some later blocks the last three digits of the block casting number are cast into the block, but these are difficult to see when the engine is in a vehicle.
BLOCK CASTING DATE
The block casting date indicates when the block itself was cast in the foundry. This date does not indicate when the motor was assembled and then later placed into the vehicle at the factory. The block casting date is usually found on the rear ledge of the block on the passenger side, but some later model blocks have the casting date on the driver's side of the rear ledge. Some of the early big blocks made in the Sixties have the block casting date located on the passenger side of the block near the freeze plug holes. On these, if the early big block is in the car you will have to get under the motor to see the casting date. Do it while the car is on a lift. The casting dates look something like this "E 12 7". The "E" stands for the month of the year with "A" being the month of January, "B" being the month of February and so on thru the letters to December. In this case the "E" stands for the month of May, the fifth month of the year and the fifth letter of the alphabet. The "12" stands for the 12th day of the month. The "7" is the year of the decade. Now unfortunately this could be '57, '67, '77, '87 or '97 depending on which part you are looking at. Some casting dates have both the year of the decade and the decade itself. They look like this "E 12 77", meaning May 12, 1977. The fun starts when you have a casting date from the first nine days of the month that look like this "D 2 6". Does that stand for April 2,1966 or does it stand for April 26th and the year is missing or hard to see? You have to look closely and carefully to be sure.
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